as we work on failover cluster, i found it as Always On, on all the servers.

I dont know how but found the DB says restoring...

the always on feature is not enabled to that particular DB.

when i try to add the DB to one of the Availability group it says:

" Failed to join the 'DB' to the availability group 'groupname' on the availability replica 'server name'

the remote copy of DB is not recovered far enough to enable database mrroring or to join it to the availability group. you need to apply the missing log records to the remote database by restoring the curent log backups from the primary database (MS SQL Server error:1408) "